Recently, with the rapid development of multimedia signal processing and transmission technology and the advent of new types of mobile TV services, such as Digital Video Broadcasting-Handheld (DVB-H), Digital Multimedia Broadcasting (DMB), etc., popularity of viewing a video on a small Liquid Crystal Display (LCD) panel has increased. FIG. 1 illustrates the state of receiving and displaying a soccer game broadcast in a DMB phone. Mainly due to costs, most of the services provide an existing screen picture for mobile broadcasting only in a reduced size.
According to an experiment which has been conducted by Knoche and others in order to measure conditions (such as the number of pixels, a bit rate, etc.) of a picture having a reduced size suitable to be displayed in a mobile terminal, it is noted that a direct reduction of a picture for display in a small-sized terminal brings loss to a detailed part in terms of vision, as described in “H. Knoche, J. D. McCarthy, and M. A. Sasse, Can Small Be Beautiful?: Assessing Image Resolution Requirements for Mobile TV, in MULTIMEDIA “05: Proceeding of the 13th annual ACM international conference on Multimedia, pp. 829-838, ACM Press, (New York, N.Y., USA), 2005.”
As described above, the loss as described above is most serious when the contents of a picture is field sports, especially, a soccer video, and becomes less serious in an order of music videos, news, and comic videos. Accordingly, in the case of a video including particular contents, there is a need for developing intelligent-type display technology which enables each viewer of the mobile terminal to view a screen picture in which only a Region-Of-Interest (ROI) is enlarged.
Herein, the ROI refers to a region the user is most interested in or pays more attention to than other regions on a screen. The ROI is utilized for situation perception contents adaptation, transcoding, intelligent-type information memagement, etc. Also, appointment of an ROI can be the first step for meaningfully analyzing a video scene, and thus it can be said that the appointment thereof is also very important art for picture analysis.
FIGS. 2A to 2D are views illustrating various score forms existing in sports videos. As noted from FIGS. 2A to 2D, during reproduction by the mobile terminal, it is necessary to automatically extract a score region and then enlage and reproduce the extracted score region.
The score region is located at a left upper portion of a screen during the display of a soccer game, and is displayed usually in a square shape having a boundary line mainly having a predetermined brightness. Also, the score region is not a natural picture but is a graphic, and is nearly always located at the same position within the screen picture. To describe in more detail, when a screen picture is a closeup shot, an environment around the score region on the screen picture is often in a static state. In this case, it is possible to extract a more accurate score region.
As a result of observing videos of various soccer games, most score regions of the videos are located within an area having dimensions of one half of the entire horizontal length and one third of the entire vertical length from a starting point of the screen. Accordingly, by limiting the range of search to this area, it is possible to efficiently extract the score region.
Meanwhile, even though there have been some researches on an advertising board region, studies on the extraction of a score region have not been actively made. As noted from “Okihisa Utsumi, K. Miura, I. Ide, S. Sakai, and H. Tanaka, “An Object Detection Method for Describing Soccer Games from Video,” in Proc. Multimedia and Expo, vol. 1, Aug. 2002, pp. 45-48,” Okihisa et al. discloses technology for discrminating a caption region from a sports ground region by using edge information. However, by the Okihisa et al.'s technology, it is not easy to discriminate a score region from an advertising board within a caption region. Also, as noted from “Ho-Sub Yoon, Young-Lae J. Bae, and Young-Kyu Yang, “A Soccer Image Sequence Mosaicking and Analysis Method Using Line and Advertisement Board Detection,” ETRI Journal, vol. 24, Dec. 2002, pp. 443-454,” Yoon et al. discloses technology for distinguishing an advertising board region from a sports ground region by using the fact that a difference exists between brightness changes in a horizontal direction of an advertising board and a sports ground. However, since there exists advertising boards having various designs and score regions having various designs, it is not easy to discriminate between the score region and the advertising board by using only the brightness difference between them. Therefore, it is desirable to extract a score region from a screen picture by using only the characteristics of the score region.